The present invention relates to devices for switching a load current by movement of a movable switching member to effect making and breaking of a set of electrical contacts. The present invention relates particularly to switching devices of the type employing an electromagnetic actuator for effecting the movement of the movable switch member; and, particularly relates to relays having an armature magnetically moved by electrical energization of a coiled conductor such as a solenoid.
Where it is required to provide a relay for switching a substantial load current in association with an electronic control circuit, it has been desired for simplicity in high-volume manufacturing to provide the relay as part of the fabrication of the circuit as, for example, built up on a printed circuit board. For applications in which space or volume is limited, it has been desired to provide such a relay and base, such as a printed circuit board combination with a minimum volume for installation in appliances controlled by the electronic circuit. Such an arrangement is desirable from a manufacturing standpoint because it is less costly to fabricate the relay as part of the printed circuit board, thereby eliminating the handling and separate attachment and wiring of a relay to the printed circuit board.
It has further been desired to provide a built-up or base-mounted relay such as for a printed circuit with a minimum volume and generally flat configuration, yet provide sufficient switching power to the relay to enable making and breaking of a set of contacts capable of handling substantial load currents, yet requiring only a very small current to the relay coil for effecting switching. Heretofore, printed circuit board mounted relays have had an overall bulkiness and awkward configuration due to the amount of ferromagnetic pole material required to provide sufficient magnetic flux to produce adequate relay actuating force with the low electrical current as, for example, the current provided by low voltage solid state signal transistors, for driving the relay coil. It has thus been desirable to find a way or means of providing a compact, low current relay which may be built upon or fabricated on a base, such as a printed circuit board, and which is capable of switching a set of contacts for handling a substantial load current, and to provide such a device which is low in manufacturing cost, to facilitate high volume mass production.